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The use of crude oil must be reduced as much as possible over the coming decades if global warming is to be brought to a halt. This also has consequences for the road construction sector which uses bitumen on a massive scale. This is a liquid mixture of various hydrocarbons that are released when converting oil into e.g. petrol or diesel.

Bitumen is used in road construction to bind asphalt and make it stronger. A group of scientists associated with the Circular Biobased Delta Foundation sought a solution and came up with the plant-based substance known as lignin.

Lignin is released in large quantities as a residual product during all kinds of industrial processes. In the production of paper, for example. At present, it is usually disposed of by being burned. Yet it has the same binding qualities as bitumen and can therefore serve as a substitute.

Test lane in Vlissingen

A preliminary test lane for daily use will be laid in Vlissingen next Friday by the Zeeland-based H4A company. They are making the bio-asphalt as well. The lignin in this case comes from a pulp factory owned by the Finnish company Stora Enso. The whole bio-asphalt project is also known as CHAPLIN-XL, which stands for Collaboration in aspHalt Applications with LIgniN. The project has received a substantial subsidy from the Netherlands Enterprise Agency (Rijksdienst voor Ondernemend Nederland).

“If the experiences with this road surface are positive, then the large-scale roll-out of it will follow throughout the rest of the country,” so states the joint press release from the universities of Wageningen and Utrecht, H4A and Circular Biobased Delta.

A piece of bio-asphalt. Photo University of Utrecht

According to the researchers, the bitumen substitute is not only good from a sustainability point of view. In recent years, the quality of bitumen has deteriorated due to the industry extracting ever more high-quality components for other applications. The developers also expect that the functional properties, such as the bio-asphalt’s rolling resistance, can be improved and that asphalt will also become quieter.

An additional sustainable advantage is that asphalt containing lignin requires much less heat during manufacture and when applied to the road surface. This differs by about 30 degrees Celsius. This leads to huge reductions in CO2 emissions.

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There is, according to the universities, a lot of interest in bio-asphalt at home and abroad. “The Netherlands is leading the way in making road construction more sustainable. Plus it has a unique position when it comes to expertise in the field of bio-asphalt.”